Multiproxy evidence of millet reliance and selective dietary change during iron age transformation in Central Europe.

This study integrates archaeobotanical and stable isotopic data to investigate dietary adaptations and crop use in past Central European societies during later prehistory (500-0 BCE), a period marked by growing social complexity and technological innovation that approximates sub-modern population structures. Using a multi-proxy approach, we analyse supra-regional datasets of plant macro-remains and human bone collagen from Bohemia, Moravia, and Slovakia, focusing on millet, the only C₄ crop cultivated in preindustrial temperate Europe, which serves as a distinct isotopic marker for tracing subsistence shifts. Archaeobotanical evidence, assessed through minimum number of individuals (MNI), ubiquity, and Representativeness Index, shows that millet cultivation was largely influenced by local environmental conditions, with no consistent temporal trend across regions. In contrast, stable carbon isotope data reveal a systemic dietary shift towards higher δ13C values during the third century BCE, coinciding with technological advances and increasing socio-economic complexity. This new trend, however, was not applied consistently: its intensity varied across sites and social groups, reflecting flexible and context-specific subsistence strategies. Non-elite individuals exhibited more pronounced shifts, while elite groups maintained more conservative, C₃-based diets. By demonstrating broad patterns alongside local variability, this study highlights the flexibility and adaptive capacity of past food production. The findings underscore the importance of integrating both regional and local scales in multi-proxy analyses and provide insights relevant to modern contexts facing globalised yet ecologically diverse agricultural challenges.